Antibiotics Flashcards
What are gram positive cocci?
Staphylcocci (including MRSA) - coagulase positive (e.g. Staph aureus) + coagulase negative (e.g. Staph epidermidis)
Streptococci: b-haemolytic (e.g. strep pyogenes, Group A strep) + a-haemolytic (e.g. strep pneumoniae - pneumococcus, strep mitior, strep mutans, strep sanguis)
Enterococci (non-haemolytic): E. faecalis - not a typical strep
Anaerobic streptococci
What are gram positive bacilli?
Aerobes: bacilus anthracis, corynebacterium diptheriae, listeria monocytogenes, nocardia species
Anaerobes: clostridium (C. difficile, C. botulinum, C. perfringens, C. tetani)
Actinomyces: A. israeli, A. naeslundii, A. odontolytic, A. viscosus
What are intracellular bacteria?
Chlamydia (C. trachomatis, C psittaci, C. pneumoniae) Coxiella burnetii Bartonella and Erlichia Rickettsia Legionella pneumophilia
What are gram negative cocci?
Neisseria: N. meningitidis, N. gonorrhoea
Moraxella: (M. catarrhalis)
What are gram negative bacilli?
Escherichia coli Shigella Salmonella PSEUDOMONAS aeruginosa HAEMOPHILUS INFLUENZAE Camplyobacter jejuni
Citrobacteria freundii, C. koseri Klebsiella pneumoniae, K. oxytoca Enterobacter aerogenes E. cloacae Serratia marascens Proteus mirabilis Morganelle morganiii Providencia species: Yersinia (Y. pestis, Y. enterocolitica, Y. paratuberculosis) Brucella species Bordetella pertussis Pasteurella multocida Vibrio cholerae Enterobacteriacaeae
What are anaerobes?
Bacteroides
Clostridium
Fusobacterium
Helicobacter pylori
What are mycobacteria?
M tuberculosis
M bovis
M leprae (leprosy)
Atypical (suspect if immunocompromised): many exist
What are spirochetes?
Borrelia burgdorferi (Lyme disease), B. recurrentis
Treponema (syphilis)
Leptospira
What are nucleic acid inhibitors?
Sulfonamides (+ and -)
Quinolones (- and +), B-lactamase resistant
Nitroimidazoles (+ and -)
Trimethoprim (+ and -)
What are cell wall inhibitors?
Penicillins (+»_space; -)
Carbapenems (+ and -), B-lactamase resistant
Monobactam (-), b-lactamase resistant
Cephalosporins (+ or -), b-lactamase resistant
Vancomycin (+»_space; -)
Teicoplanin (+»_space; -)
What are protein inhibitors?
Tetracyclines (+ and -) Aminoglycosides (- >> +) Macrolides (+ >> -) Streptogramins Chloramphenicol (+ and -)
What are sulfonamides?
Sulfadiazine, Sulfamethoxazole (+ and -)
Bacteriostatic, orally active, action prevented by pus (P-amino benzoic acid)
Widespread resistance to hospital acquired infections
Nausea and vomiting
Side effects: hypersensitivity reactions (common in drugs based in sulphur), bone marrow suppression
Replaced by antimicrobials with less resistance and less toxicity
What are quinolones?
Ciprofloxacin, norfloxacin nalidixic acid
- and + (-ve better, but broad spectrum)
Beta-lactamase organisms resistant to penicillins and some cephalosporins
Good presumptive treatment but avoid in sepsis, does not cross BBB. Inhibits P450.
Uses: pyelonephritis, dysentry, severe gastroenteritis, pseudomonas
What are nitroimidazoles?
Metronidazole, tinidazole
Bactericidal, broad spectrum, important in serious anaerobic infections e.g. sepsis, orally active + against H. pylori
Interacts with ethanol, warfarin metabolism,
Bitter taste - (goes into breast milk)
Uses: PID, BV, trichomoniasis, anaerobic sepsis, infected wounds, C. difficile colitis, post surgery
What are penicillins?
Benzylpenicillin +»>- (pen G)
Phenoxymethylpenicillin (pen V; less active against -ve)
Flucloxacillin (methicillin not used anymore) +»>-
Amoxicillin +»-
Azlocicillin +>- and Piperacillin +>- (used for pseudomonas)
Bactericidal, fairly broad spectrum but better for gram positive
First line in rare diseases as orally available so work in range of areas, good bioavailability, orally active so work in range of areas, low adverse effects
Used for: pseudomonas, syphillis, meningitis (benzylpenicillin for pre-hospital management), UTI, bronchitis, pneumonia (anthrax, diphtheria, gas gangrene, leptospirosis, Lyme disease)
Hypersensitivity 1-10% of exposed individuals (0.05% anaphylaxis), more likely if atopic, should not be given β lactam antibiotics
Encephalopathy
Excreted in kidney: make sure no renal insufficiency, Na penicillin, K penicillin, often given IV
What are B-lactam antibiotics?
Has B lactam ring, however, not all B-lactam antibiotics are affected by the B-lactamase enzyme
Penicillins (flucloxacilin is B-lactamase resistant)
Cephalosporins
Vancomycin
Teicoplanin
Clauvulanic acid also has ring and inhibits beta-lactamase, given with amoxicillin (co-amoxiclav)
What are cephalosporins?
Broad-spectrum, bactericidal (cefalexin, cefuroxime, cefotaxime, ceftriaxone, cefaclor, cefradine, cefalexin etc)
Cefalexin (po) +»_space;>- -
Cefuroxime (po) -»_space; + (B-lactamase resistant, cross BBB)
Cefotaxime iv -»_space; + (B-lactamase resistant + cross BBB)- may lead to opportunistic inf e.g. Candida, C diff.
Used in surgical prophylaxis, ‘blind’ meningitis therapy (CEFTRIAXONE), UTI, peritonitis, pneumonia, septicaemia, biliary tract. CEFTRIAXONE for gonorrhoea.
Renal excretion, reduced dose in impairment
Note: 0.5-6.5% of pencillin sensitive pt will also react to cephalosporins. If cephalosporin essential in these pts as no suitable alternative, certain drugs from this class are better than others (e.g. cefotaxime and ceftriaxone can be used with caution)
What is C. diff caused by? Tx?
High risk: cephalosporins, clindamycin, co-amox, ciprofloxacin. Medium risk: amoxicillin, macrolides, co-trimoxazole
Tx = metronidazole
What are monobactams?
Aztreonam IV: gram -ve aerobic only
- Beta lactamase resistant, side-effects similar to penicillins, no cross hypersensitivity, can be used in penicillin sensitive patients
Kidney excretion + short half life
Liver and marrow toxicity (should be bacteria specific as no cell walls, but are problems in liver and marrow as well)
Uses: H. influenzae, pseudomonas, gonorrhoea, meningitis
What are tetracyclines?
Tetracycline, doxycline, + and -
Bacteriostatic, broad spectrum, widespread resistance therefore use limited
3,4,5,6 months of treatment, because lives in skin - reacts with sun, photosensitive response
Erythema and photosensitisation, tooth discolouration (causes more calcium to be stored in the teeth)
Uses: chlamydia, plague, brucellosis, zoonotic disease (undulant fevers, sweating wet hay like smell, migratory arthralagia and myalgia), CAP, cholera
What are aminoglycosides?
Gentamicin, Streptomycin, Neomycin
- > +
Spectrum + resistance varies with individual drug, poor penetration of BBB, not orally active
Resistance a problem: bacteria makes drug degrading enzymes
Serious side effects:
* ototoxicity, (deafness) * nephrotoxicity (netilmicin less toxic) * Renal assessment and drug monitoring required
Uses: MRSA, Gram -ve septicaemia, endocarditis -Streptococci or Staph
What are macrolides?
Erythromycin +»_space;> - (po)
Clarithromycin + > - (po, iv)
Azithromycin + > - (po, iv)
Similar range of action + efficacy to penicillins, alternative for penicillin sensitive individuals (aztreonam or clarithromycin can be used for penicillin allergy)
Can cause diarrhoea + jaundice, may have CYP450 interactions, blocks metabolism of warfarin and some antihistamines, also interacts with omeprazole (both inhibit same CYp450 enzyme)
Uses: Respiratory infection, otitis media, pertussis, legionnaire’s disease, bronchitis, H. pylori
What is chloramphenicol?
Bacteriostatic, orally active
+ > -ve
Very toxic: bone marrow suppression, effects on newborns ‘grey baby syndrome’ - builds up in fetus, tends to only be used externally e.g. eye drops
Acts in same way as erythromycin but wider spectrum
Uses: conjunctivitis, meningitis, haemophilus influenza
Reserved for serious infections because of all of side effects
Ones to remember
- Sulfamethoxazole
- Ciprofloxacin
- Metronidazole
- Trimethoprim
- Flucloxacilin
- Amoxicilin
- Aztreonam
- Cephalosporins
- Vancomycin
- Tetracycline
- Clarithromycin (H. pylori)
- Chloramphenicol
- so toxic - used outside body now
Dr F - Abx for gram positive
Flucloxacillin, benzylpenicillin, erythromycin, doxycycline, fusidic acid, clindamycin, vancomycin
Dr F - Abx for gram negative
Gentamicin, trimethoprim, co-amoxiclav, cefalosporins
Dr F - Abx for broad spectrum
Cefuroxime, cefotaxime, tetracyclines
Dr F - Abx for extended broad spectrum
Ciprofloxacin, ceftazidime, piptazobactam, meropenem
Dr F - Abx for anaerobic
Metronidazole, clindamycin,
Dr F - antiviral / fungals
Viral: Acyclovir, ganciclovir
Fungal: Fluconazole, caspofungin, amphotericin